[Virtio-fs] [PATCH v4 0/2] virtiofsd: Improve io bandwidth by replacing pwrite with pwritev

Sun Aug 11 11:15:56 UTC 2019

Hi,

On Sun, Aug 11, 2019 at 10:46:02AM +0800, piaojun wrote:
> 
> 
> On 2019/8/11 10:06, Eric Ren wrote:
> > Hi jun,
> > 
> > On Fri, Aug 09, 2019 at 08:50:12AM +0800, piaojun wrote:
> >> >From my test, write bandwidth will be improved greatly by replacing
> >> pwrite with pwritev, and the test result as below:
> > 
> > Could you share more information about this testing?
> > 
> > - args for qemu: cache size?
> > - args for virtiofsd: which cache mode？
> > - DAX is used, right?
> 
> DAX is disabled, as this optimization only works on Host side.

OK, thanks for the info.

The test runs in KATA container, which use DAX as its default mount
option.

> 
> > 
> > - which kind of disk are you using, what's then IOPS/BW limit?
> > 
> > I tried this patch with HDD disk - IOPS:5000, BW: 140MB/s.
> 
> I used EXT4 and ramdisk as backend device.
> 
> > 
> > - VM: 4 vcpus, 8G mem
> > - cache=always, cache-size=8G, DAX
> > - fio job
> > 
> > ```
> > [global]
> > fsync=0
> > name=virtiofs-test
> > filename=fio-test
> > directory=$mntdir   # share dir for test sitting on the disk
> > rw=randwrite
> > bs=4K
> 
> *bs* should be 1M for bandwidth test which makes writev works well.

Yes, but seq write "rw=write" is also good fr BW test, right?

> 
> > direct=1
> > numjobs=1
> > time_based=0
> > 
> > [file1]
> > size=2G
> > io_size=40M
> > ioengine=libaio
> > iodepth=128
> > ```
> > - without this patch
> > 
> > ```
> > file1: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=128
> > fio-3.1
> > Starting 1 process
> > 
> > file1: (groupid=0, jobs=1): err= 0: pid=11: Sat Aug 10 11:33:29 2019
> >   write: IOPS=985, BW=3942KiB/s (4037kB/s)(40.0MiB/10390msec)
> > ```
> > 
> > - with this patch applied
> > 
> > ```
> > file1: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=128
> > fio-3.1
> > Starting 1 process
> > 
> > file1: (groupid=0, jobs=1): err= 0: pid=10: Sat Aug 10 15:31:57 2019
> >   write: IOPS=1056, BW=4224KiB/s (4326kB/s)(40.0MiB/9696msec)
> > 
> > ```
> > 
> > the number is even worse than 9pfs.
> 
> Please modify your testcase as mentioned above, and share your result
> again. I'm glad to find out where the problem is.

Will come back if I get the number.

Thanks,
Eric

> 
> Jun
> 
> > 
> > Thanks,
> > Eric
> > 
> >>
> >> ---
> >> pwrite:
> >> # fio -direct=1 -time_based -iodepth=64 -rw=randwrite -ioengine=libaio -bs=1M -size=1G -numjob=16 -runtime=30 -group_reporting -name=file -filename=/mnt/virtiofs/file
> >> file: (g=0): rw=randwrite, bs=1M-1M/1M-1M/1M-1M, ioengine=libaio, iodepth=64
> >> ...
> >> fio-2.13
> >> Starting 16 processes
> >> Jobs: 16 (f=16): [w(16)] [100.0% done] [0KB/886.0MB/0KB /s] [0/886/0 iops] [eta 00m:00s]
> >> file: (groupid=0, jobs=16): err= 0: pid=5799: Tue Aug 6 18:48:26 2019
> >> write: io=26881MB, bw=916988KB/s, iops=895, runt= 30018msec
> >>
> >> pwritev:
> >> # fio -direct=1 -time_based -iodepth=64 -rw=randwrite -ioengine=libaio -bs=1M -size=1G -numjob=16 -runtime=30 -group_reporting -name=file -filename=/mnt/virtiofs/file
> >> file: (g=0): rw=randwrite, bs=1M-1M/1M-1M/1M-1M, ioengine=libaio, iodepth=64
> >> ...
> >> fio-2.13
> >> Starting 16 processes
> >> Jobs: 16 (f=16): [w(16)] [100.0% done] [0KB/1793MB/0KB /s] [0/1793/0 iops] [eta 00m:00s]
> >> file: (groupid=0, jobs=16): err= 0: pid=6328: Tue Aug 6 18:22:17 2019
> >> write: io=52775MB, bw=1758.7MB/s, iops=1758, runt= 30009msec
> >> ---
> >>
> >> This patch introduces writev and pwritev for lo_write_buf(). I tried my
> >> best not doing harm to the origin code construct, and there will be
> >> some *useless* branches in fuse_buf_copy_one() which are hard to judge
> >> if they will be useful in the future. So I just leave them alone
> >> safely. If the cleanup work is necessary, please let me know.
> >>
> >> v2
> >>   - Split into two patches
> >>   - Add the lost flags support, such as FUSE_BUF_PHYS_ADDR
> >>
> >> v3
> >>   - use git send-email to make the patch set in one thread
> >>   - move fuse_buf_writev() into fuse_buf_copy()
> >>   - use writev for the src buffers when they're alread already mapped by the daemon process
> >>   - use calloc to replace malloc
> >>   - set res 0 if writev() returns 0
> >>
> >> v4
> >>   - iterate from in_buf->buf[0] rather than buf[1]
> >>   - optimize the code to make it more elegant
> >>
> >> Jun Piao (2):
> >>   add definition of fuse_buf_writev().
> >>   use fuse_buf_writev to replace fuse_buf_write for better performance
> >>
> >> Signed-off-by: Jun Piao <piaojun at huawei.com>
> >> Suggested-by: Dr. David Alan Gilbert <dgilbert at redhat.com>
> >> Suggested-by: Stefan Hajnoczi <stefanha at redhat.com>
> >> ---
> >>  buffer.c      |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
> >>  fuse_common.h |   14 ++++++++++++++
> >>  seccomp.c     |    2 ++
> >>  3 files changed, 64 insertions(+)
> >> --
> >>
> >> _______________________________________________
> >> Virtio-fs mailing list
> >> Virtio-fs at redhat.com
> >> https://www.redhat.com/mailman/listinfo/virtio-fs
> > .
> > 